Photographic material comprising a silver halide emulsion containing an anti-bronzing agent



United States Patent 3,203,800 PHOTOGRAPHIC MATERIAL COMPRISING A SIL-VER HALIDE EMULSION CONTAINING AN ANTI-BRONZING AGENT Jozef FransWillenis, Hendrik Adolf Pattijn, and Gerard Michiel Sevens,Wilrijk-Antwerp, Belgium, assignors to Gevaert Photo-Producten N.V.,Mortsel-Antwerp, Belgium, a company of Belgium No Drawing. Filed Jan. 7,1963, Ser. No. 249,615 Claims priority, application Belgium, Jan. 5,1962, 41,269, Patent 612,311 4 Claims. (Cl. 96-67) This inventionrelates to photographic material which is protected against bronzingcaused by hot glazing or mechanical drying.

The images obtained in light-sensitive silver halide emulsion layersoften undergo changes during processing among others during hot glazingor mechanical drying, at high temperature. During these treatments lossof density occurs easily by the so-called bronzing of the silver image.

It is known to add small amounts of chemical compounds tolight-sensitive materials containing silver halide or to certainprocessing baths in order to avoid decrease of density as a result ofhigh glossing.

. In addition to the fact that these compounds do not completelycounteract bronzing, they still show other disadvantages when beingadded to a silver halide emulsion.

The most important disadvantage is their mostly very strongdesensitizing action.

It has now been found that by adding compounds according to thefollowing general formula:

R represents an aryl group or a substituted aryl group,

R represents a hydrogen atom, an alkyl group, a substituted alkyl group,an aryl group or a substituted aryl p,

Each of R and R (same or ditferent) represent a hydrogen atom, a loweralkyl group or a substituted lower alkyl group, and

n represents a positive integer from 1 to 5,

to the light-sensitive silver halide emulsion layer and/or to at leastone water-permeable layer of the light-sensitive material at the sameside of the support as said emulsion layer, the disadvantages caused byhot glazing or mechanical drying are prevented.

Contrary to suchlike compounds with a free mercapto function, thesecompounds have no desensitizing action on the silver halide emulsion.

Suitable compounds corresponding to the above general formula are e.g.:

silver salt of a-mercapto butyric acid-p-toluidide silver salt offl-mercapto-propionic acid-p-toluidide @NH-G O-CHr-SAg silver salt ofa-mercapto-acetanilide 3,203,800 Patented Aug. 31, 1965 ice silver :saltof a-mercapto-butyric acid-l-naphthalide silver salt ofa-mercapto-acetic acid-Z-naphthalide silver salt ofN-phenyl-a-mercapto-butyric acid-anilide silver salt ofa-mercapto-propionic acid-p-toluidide silver salt ofa-mercapto-isobutyric acid-p-toluidide The light-sensitive silver halideemulsion wherein compounds according to the present invention can beincorporated can be any silver halide emulsion such as a gelatinosilverchloride emulsion, a gelatino-silver chloro-bromide emulsion, agelatino-silver chloroiodide emulsion, a gelatino-silver bromideemulsion, a gelatino-silver bromoiodide emulsion, and a gelation-silverchlorobromoiodide emulsion. The emulsion can be sensitized chemically aswell as optically. It may moreover contain all known additives such asanti-fogging agents, stabilizers, hardening agents, softening agents anddispersiing agents.

The compounds according to the present invention can be added during anystage of the preparation of the emulsion, e.g. during the formation ofthe silver halide or during the physical or chemical ripening, butpreferably after the chemical ripening.

The amount, in which the compounds according to the present inventionmay be added depends on the emulsion used but it generally varies from 2to 20 g. per 1000 g. of silver nitrate.

The compounds according to the present invention are present in thelight-sensitive composition in the form of a colloidal dispersion.

When using the compounds according to the present invention, there is noloss in sensitivity or contrast of the photographic material, whereasthe use of the compounds in their free mercapto form or as alkalinemetal or ammonium salt would cause a considerable loss in sensitivity.

It is also possible to incorporate the compounds according to thepresent invention in a hydrophilic layer adjacent to the light-sensitivelayer e.g. in the covering layer, or in another layer from which, duringfixation, they can e.g. diffuse to the silver halide emulsion layer. Theconcentration in which the compounds according to the invention areincorporated into these layers is mostly the same as or slightly higherthan their concentration when added to the light-sensitive layer.

The compounds according to the invention are sometimes incorporated intoa processing bath e.g. in the fixing bath.

The combination of at least one of the compounds according to thisinvention with poly(N-vinylpyrrolidone) gives as anti-bronzing agentstill better results. In that case poly(N-vinylpyrrolidone) can beincorporated into the light-sensitive laver and/or into an other waterpermeable layer at the same side of the support as the light-sensitivelayer, in a concentration which preferably varies from 20 to 80 g. permole of silver halide.

The following are examples illustrating the properties of photographicmaterials containing anti-bronzing agents according to the presentinvention.

Example 1 To an ammoniacal gelatino-silver bromoiodide emulsioncontaining 3.5 mol percent of silver iodide based on the total amount ofsilver halide and having a medium gradation are added per mole of silverhalide 1.9 g. of the silver salt of a-mercapto-butyric acid-p-toluididein the form of a dispersion. This emulsion is applied on a baryta-coatedpaper support in such a way, the light-sensitive layer contains per sq.m. an amount of silver halide equivalent to 2 g. of silver nitrate. Onthis emulsion layer a gelatin-containing convering layer is coated. Thismaterial is exposed under a step-wedge, developed, fixed and rinsed.Then it is subjected to high glossing by pressing its image side againsta heated polished metal surface. The reflection densities are measuredby means of a MacBeth densitometer before and after subjecting thematerial to high glossing. The following results are obtained:

Maximum density After subjecting to high glossing Before subjecting tohigh glossing Example 2 Three materials are prepared starting from anammoniacal gelatino-silver bromoiodide emulsion as described inExample 1. In the preparation of the first material (the comparisonmaterial), no anti-bronzing agent is added to the emulsion. In thepreparation of the second and the third material, respectively of 0.45g. of the silver salt of a-rnercapto-butyric acid-p-toluidide and 0.45g. of the silver salt of ,B-mercapto-propionic acid-ptoluidide are addedto the emulsion per mol of silver halide. Moreover, in the preparationof the three emulsions, 60 g. of poly(N-vinylpyrrolidone) are added permol of silver halide. baryta-coated paper supports in such a way, thatthe lightsensitive layer contains per sq. m. an amount of silver Theemulsions are applied to halide equivalent to 2.2 g. of silver nitrate.On the emulsion layers gelatin-containing covering layers are coated.

The three materials thus obtained are then treated in the same way as inExample 1. The results are the following.

Maximum density Before sub- After subjecting to jecting to high glossinghigh glossing First material (comparison material) 2. 04 1. 03 Secondmaterial 2. 10 2. 06 Third material 2. 11 2. 02

- of the support as the light-sensitive silver-halide emulsion layer.

2. A photographic material comprising a support and at least onelight-sensitive silver halide emulsion layer and containing the silversalt of a-mercapto-butyric acid-ptoluidide in at least one waterpermeable layer which is situated at the same side of the support as thelightsensitive silver halide emulsion layer.

3. A photographic material comprising a support and at least onelight-sensitive silver halide emulsion layer and containing the silversalt of fl-mercapto-propionic acid-p-toluidide in at least onewater-permeable layer which is situated at the same side of the supportas the light-sensitive silver halide emulsion layer.

4. The photographic material of claim 1 wherein the water-permeablelayer contains poly(N-vinylpyrrolidone).

References Cited by the Examiner UNITED STATES PATENTS 3,080,230 3/ 63Haydn et al. 96--95 FOREIGN PATENTS 1,090,385 3/55 France.

794,637 5/58 Great Britain. 607,639 10/60 Canada. 1,119,119 12/61Germany.

NORMAN G. TORCHIN, Primary Examiner.

1. A PHOTOGRAPHIC MATERIAL COMPRISING A SUPPORT AND AT LEAST ONELIGHT-SENSITIVE SILVER-HALIDE EMULSION LAYER AND CONTAINING THE SILVERSALT OF A MEMBER OF THE GROUP CONSISTING OF A-MERCAPTO BUTYRICACID-P-TOLUIDIED, BMERCAPTO-PROPIONIC ACID-P-TOLUDIDE,A-MERCAPTO-ACENTANILIDE, A-MERCAPTOBUTYRIC ACID-L-NAPHTHALIDE,A-MERCAPTOACTEIC ACID-2-NAPHTHALIDE N-PHENYL-A-NERCPTO-BUTYRICACID-ANILIDE, A-MERCAPTO-PROPIONIC ACID-P-TOLUIDIDE, ANDA-MERCAPTO-ISOBUTYRIC ACID-P-TOLUIDIDE IN AT LEAST ONE WATER-PERMEABLELAYER WHICH IS SITUATED AT THE SAME SIDE OF THE SUPPORT AS THELIGHT-SENSITVE SILVER-HALIDE EMULSION LAYER.